Introduction to the Internet and the World Wide Web

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Introduction to the Internet and the World Wide
Web
Tutorial 1

• History, Structure, and Getting Connected

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Objectives

• Obtain an overview of the information and tools
  that are available on the Internet
• Learn what computer networks and internets are
  and how they work
• Find out how the Internet and the World Wide Web
  began and grew
• Compare different methods for connecting to the
  Internet

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Internet and World Wide WebAmazing Developments

• The Internet is a large collection of computers
  all over the world connected to one another.
• One of the most amazing technological
  developments of the 20th century.
• The World Wide Web is a subset of computers on
  the Internet that has helped make Internet
  resources available to people who are not
  computer experts.

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Internet and World Wide WebAmazing Developments

• New Ways to Communicate
• E-mail
• Electronic discussions
• Instant messaging
• Information Resources and Software
• Newspapers magazines
• Government documents
• Research reports books
• Software download sites

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Internet and World Wide WebAmazing Developments

• Doing Business Online
• Electronic storefronts
• Coordinate worldwide operations
• Recruit employees
• Entertainment
• Review restaurants, movies, theater, musical
  events and books.
• Interactive games
• Follow sports teams

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Antivirus

• Wont learn till later, but you should have
  antivirus software (and firewall) on your
  computer.
• Norton
• McAfee
• Etc.
• May be provided by your ISP

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Computer Networks

• Network a collection of connected computers.
• Network Interface Card (NIC) a card used to
  connect a computer to a network of other
  computers.
• Server computer that accepts requests and shares
  some or all of its resources with computers to
  which it is connected.

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Client/Server Local Area Networks

• Client computer connected to a server.
• Network Operating System software that runs on a
  server.
• Client/Server Networks one server computer
  sharing its resources with multiple client
  computers.
• Local Area Network (LAN) network of computers
  located close to each other.

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Client/Server LAN
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Client/Server Local Area Networks

• Node or network node each computer, printer, or
  other device connected to a network.
• Minicomputer and mainframe computer larger, more
  expensive computers used by businesses and
  organizations to process large amounts of work.

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Connecting Computers to a Network Types of
Cable

• Twisted Pair oldest type, used by telephone
  companies, usually Category 1.
• Coaxial Cable 20 times faster than Category 1,
  more expensive
• Category 5 carries signals between 10 100
  times faster than coaxial cable, easy to
  install.
• Fiber-optic cable most expensive, transmits
  pulsing beams of light through very thin strands
  of glass, fastest transmission rate.

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Types of Cable
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Wireless Networks

• Becoming more common as costs drop.
• Old buildings -- expensive to install wiring.
• Companies which use laptop computers.
• Schools -- classrooms, libraries, and study
  lounges.
• Homes.

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Wide Area Networks

• WAN a network of networks or an internet.
• Internet a worldwide collection of
  interconnected networks owners have voluntarily
  agreed to share resources and network connections.

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Connectivity Circuit Switching

• Circuit switching
• centrally controlled
• single-connection method
• used by most local telephone traffic today
• Vulnerable to destruction of signal control point
  or any link in the single path that carries the
  signal.

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Connectivity Packet Switching

• Packet-switching files and messages broken down
  into packets and labeled electronically with
  codes for their origin and destination.
• Packets travel from computer to computer along
  the network until they reach their destination.
• Routers determine the best way for a packet to
  move towards its destination.

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Connectivity Packet Switching

• Datagram packet with routing info.
• Packet-switched networks more reliable
• rely on multiple routers instead of central point
  of control.
• each router can send individual packets along
  different paths if parts of the network are not
  operating.

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Origins of the Internet

• DARPA (Defense Advanced Research Projects Agency)
  researchers connected first computer switches in
  1969.
• ARPANET grew over next three years to include
  over 20 computers. Grandpa of Internet.

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Open Architecture Philosophy

• Independent networks should not require any
  internal changes to be connected to the
  Internet.
• Packets that do not arrive at their destinations
  must be retransmitted from their source network.
• The router computers do not retain information
  about the packets they handle.
• No global control will exist over the network.

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Open Architecture Philosophy

• Protocol Rules for formatting, ordering, and
  error-checking data sent across a network.
• New set of protocols developed in 1970 by Vincent
  Cerf and Robert Kahn
• Transmission Control Protocol
• Internet Protocol
• (TCP/IP)

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Open Architecture Philosophy

• TCP rules used by computers on a network to
  establish and break connections.
• IP rules for routing of individual data packets.
• TCP/IP used today in LANs and on the Internet.
• Vincent Cerf considered to be the father of the
  Internet by many.

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Birth of E-MailA New Use for Networks

• Ray Tomlinson, an ARPANET researcher, wrote a
  program that could send and receive messages over
  the network in 1972.
• E-mail was born and rapidly became widely used in
  the computer research community.
• ARPANET continued to develop faster and more
  effective network technologies.
• Began sending packets by satellite in 1976.

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More New Uses for Networks Emerge

• File Transfer Protocol (FTP) - transfer files
  between computers.
• Telnet - users log in to their computer accounts
  from remote sites.
• Mailing lists (LISTSERV), information posting
  areas (Usenet), and adventure games among new
  applications appearing on the ARPANET.

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Commercial Interest Increases

• National Science Foundation (NSF) prohibited
  commercial network traffic on its networks.
• Larger firms built TCP/IP-based WANs that used
  leased telephone lines to connect field offices
  to corporate headquarters.
• NSF permitted commercial access. Initially there
  was resentment but business invested much money,
  speed increased and costs fell.

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Commercial Interest Increases

• Intranet LANs or WANs that use TCP/IP protocol
  but do not connect to sites outside the firm.
• Extranet an intranet that allows selected
  outside parties to connect.
• ARPANET grew from 4 computers in 1969 to over
  300,000 by 1990.

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Growth of the Internet

• Formal definition of Internet was adopted in 1995
  by the Federal Networking Council (FNC).

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From Research Project to Information
Infrastructure
Growth in number of Internet hosts
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Growth of the Internet

• Number of hosts connected to Internet includes
  only computers directly connected to the
  Internet.
• Internet traffic now carries more files that
  contain graphics, sound, and video, so Internet
  files have become larger.

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New Structure for the Internet

• Organized around four network access points
  (NAPs), operated by four different
  tele-communications companies.
• The four companies and their successors sell
  access to the Internet through their NAPs to
  organizations and businesses.
• The NSFnet still exists for government and
  research use.

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New Structure for the Internet

• More than 180 million connected host computers
  and more than 700 million worldwide Internet
  users.
• TCP/IP numbering system that identifies users on
  the Internet is running short of numbers.
• IP version 4 provides a maximum of about 4
  billion addresses.
• IP version 6 approved in 1997 by the IETF allows
  existing users to continue accessing the Internet
  while new system is being implemented.

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New Structure for the Internet

• The Internet has become one of the most amazing
  technological and social accomplishments of the
  century.
• Computers linked to this interconnected network
  are located in almost every country of the world.
  
• Billions of dollars change hands every year over
  the Internet.

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World Wide Web

• World Wide Web a way of thinking about
  information storage and retrieval. Can view
  multimedia documents (text, graphics, audio, and
  video.
• Web software that runs on some of the computers
  connected to each other through the Internet.
• In 1990, Tim Berners-Lee of CERN developed the
  World Wide Web.
• HTTP Protocol that transfers Web pages.

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Hypertext

• Hypertext Markup Language (HTML) a language that
  includes a set of codes (or tags) attached to
  text.
• Hypertext Server a computer that stores files
  written in HTML other computers connect to it
  and read files.
• Hypertext Link (hyperlink) points to another
  location in the same or another HTML document.

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Hypertext

• Web Browser software that lets users read HTML
  documents and move from one HTML document to
  another through hypertext link tags in each
  file.
• HTML is a subset of Standard Generalized Markup
  Language (SGML) which has been used for many
  years to manage large document-filing systems.

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GUI

• GUI (graphical user interface) a way of
  presenting program output using pictures, icons,
  and other graphical elements.
• e.g. CoreFTP vs. command line
• Much easier to learn and use
• Point and click

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Hypertext and Graphical UserInterfaces Come to
the Internet

• Mosaic first GUI program to read HTML and use
  HTML documents hyperlinks to navigate from page
  to page on computers anywhere on the Internet.

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Commercializationof the Internet

• Businesses quickly recognized profit-making
  potential offered by a world-wide network of
  easy-to-use computers.
• The Netscape Navigator Web browser was an instant
  success.
• Internet Explorer Web browser entered the market
  soon after Netscapes success became apparent.

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Growth of the World Wide Web
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Connection Options

• NAPs (network access points) offer connections to
  large organizations and businesses.
• Those businesses provide Internet access to other
  business and individuals as ISPs.
• Internet service providers (ISPs) provide
  customers with software to connect to the ISP,
  browse the Web, send and receive e-mail messages,
  and perform other Internet-related functions.

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Hierarchy of Internet Service Providers
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Connection Bandwidth

• Bandwidth amount of data that can travel through
  a communications circuit in one second.
• Bandwidth depends on the type of connection ISP
  has to the Internet and the kind of connection
  you have to the ISP.
• Available bandwidth for any type network
  connection between two points is limited to
  narrowest bandwidth that exists in any part of
  the network.

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Connection Bandwidth

• Bandwidth measured in bits per second (bps).
• When you extend your network beyond a local area,
  the speed of the connection depends on type of
  connection used.
• POTS (or plain old telephone service) is one way
  to connect computers or networks over longer
  distances. 28-56 kbps

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Connection Bandwidth

• Digital Subscriber Line (DSL) higher grade of
  service offered by some telephone companies.
• Integrated Services Digital Network (ISDN) first
  technology developed using a DSL protocol offers
  bandwidths up to 256 Kbps.
• Asymmetric Digital Subscriber Line (ADSL) offers
  transmission speeds ranging from 16 Kbps to 9
  Mbps.
• T1 or T3 connections often used by businesses
  and large organizations much more expensive than
  POTS or ISDN connections.

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Connection Bandwidth

• Cable connection increasingly available in the
  U.S. can deliver up to 10 Mbps to an individual
  user.
• Satellite connection appealing to users in
  remote areas can download at a bandwidth of
  approximately 400 Kbps.
• Fixed-point wireless connections offered by
  some companies
• technology similar to wireless LANs
• limited and more expensive.

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Internet2

• Internet 2 operated by group of research
  universities and the NSF has backbone bandwidths
  greater than 10 Gbps.
• Develop new technologies that will be rapidly
  deployed to expand the Internet.

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http//www.internet2.edu/about/

• Internet2 is a consortium being led by 207
  universities working in partnership with industry
  and government to develop and deploy advanced
  network applications and technologies,
  accelerating the creation of tomorrow's Internet.
  Internet2 is recreating the partnership among
  academia, industry and government that fostered
  todays Internet in its infancy.
• The primary goals of Internet2 are to
• Create a leading edge network capability for the
  national research community
• Enable revolutionary Internet applications
• Ensure the rapid transfer of new network services
  and applications to the broader Internet
  community.

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Connecting Through YourSchool or Employer

• Many universities and employers offer Internet
  access to their students, faculty members, and
  employees.
• Most schools and employers have an acceptable use
  policy (AUP) that specifies the conditions under
  which you can use their Internet connections.
• possibly least expensive option
• should carefully consider if limitations placed
  on use of the Internet are greater than the
  benefits

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Connecting Through anInternet Service Provider

• Reliable connectivity at a reasonable price.
• Terms of AUPs usually less restrictive.
• Offer modem connections to individuals and higher
  speed connections to businesses. May also offer
  DSL connections to individual and business
  customers.
• Quality of service may deteriorate significantly
  over time if ISP adds many new customers without
  expanding bandwidth.

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Connecting Through a DSL Provider

• Connections increasingly available in the U.S.
  and a few other countries.
• Significantly faster connection that dial-up
  service.
• Speeds and subscription rates similar to cable
  modems.
• Sometimes long delays in installation and repair
  services.

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Connecting Through YourCable Television Company

• Cable modem converts digital signals into
  radio-frequency analog signals similar to
  television transmission signals.
• Signals travel over the same lines that carry
  cable television signals.
• Cable connection is up to 170 times faster than a
  telephone line connection.
• Cable connection is not available in all areas.

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Connecting by Satellite

• Satellite Internet connections may be only option
  available in rural areas.
• Speeds and monthly fees similar to those of cable
  and DSL providers.
• Installation fee usually considerably higher
  because the dish must be installed and aimed at
  the satellite.

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Summary

• The Internet and the Web began in the military
  and research communities.
• The Internet and the Web have become an important
  worldwide infrastructure.
• The Internet and the Web support many resources
  through one of the most powerful communication
  tools the world has ever known.
• There are a number of options for connecting your
  computer and the computers of businesses and
  other organizations to the Internet.